hitssquad said:
The size of the asteroid in the movie was, I think, overkill for a "global killer," and the idea that something that large could be split in half with a nuke small enough to fit in a shuttle cargo bay I do not find realistic.
hitssquad,
You don't need to split the asteroid in half. You just have to blow enough
off so that the recoil will send the rest of the asteroid into a trajectory
that misses Earth.
The particulars with how to deal with an Earth-intersecting asteroid was
the topic of a workshop for scientists held about 10 years ago at
Lawrence Livermore National Laboratory. It was called "The Planetary
Defense Workshop" and the proceedings are posted online at the LLNL
website:
http://www.llnl.gov/planetary/
You can read papers of how to use "kinetic kill" vehicles, lasers, and
other forms of non-nuclear defenses - in addition to the nuclear weapons.
In particular, if you look at the study by Petrov, et. al; "The Effect of
Neutron Radiation from a Nuclear Explosion on an Asteroid", in the
bottom paragraph on page 5; the authors conclude that the fraction
of the bomb's energy that is absorbed doesn't depend on density. Their
assumed asteroid composition is silicon dioxide [ which is what makes
up sand].
A nuke that would fill the shuttle's cargo bay would be HUGE. Remember,
our current strategic warheads are small enough to fit several on a
small missile, two dozen of which fits in a submarine. Each bomber
aircraft can also carry several bombs - and bomb bays are not that big.
Dr. Gregory Greenman
Physicist